Supply of the dairy cow with amino acids from dietary protein

Microbial protein produced in the rumen is not sufficient to meet the requi rement for amino acids of the high producing dairy cow. The microbial prote in thus need to be supplemented with a certain amount of undegraded protein which match the microbial protein both quantitatively and qualitatively to enable an efficient utilization for milk production. This paper summarizes findings with respect to amino acid composition and digestibility of micro bial amino acids. The main emphasis is however on recent findings with resp ect to degradability and digestibility of individual amino acids in feed pr oteins. The results seem to indicate that degradability and digestibility e stimates obtained for nitrogen may not always apply to individual amino aci ds. It is concluded that more research is needed to identify the ideal prof ile of the amino acids absorbed from the intestine of lactating cows. Resul ts of such efforts are needed to compose an ideal protein supplement eventu ally by using protected amino acids to balance the microbial protein to mee t the amino acid requirement of dairy cattle with a minimum of rumen undegr aded protein.